Abstract
Internodal cells of a brackish water charophyte Lamprothamnium succinctum regulate their turgor pressure upon hypotonic treatments within 1 h. During the regulation, vacuolar KCl is released to regulate the turgor pressure. Cytoplasmic concentrations of K+, Na+ and Cl- after hypotonic turgor regulation were analyzed to know effects of efflux of vacuolar KCl through the cytoplasm. They were measured with an ion chromatography using cells whose vacuoles were replaced with artificial cell saps free from those inorganic ions. Immediately after the end of hypotonic turgor regulation, cytoplasmic concentration of K+ decreased and then gradually increased. Cytoplasmic concentration of Cl- transiently decreased. On the contrary, cytoplasmic concentration Na+ increased transiently. The same tendencies were observed in response to a stronger hypotonic stress. Cytoplasmic concentrations of K+, Na+ and Cl- were regulated against the transient changes induced by hypotonic treatments.
